Based upon the assumption that, in the intrinsic disorder of this oxide, O-ion vacancies predominated at low O pressures and O-ion interstitials predominated at high O pressures, a model was developed which explained the preferential formation of mobile interstitial Si ions at high O pressures by doping with Ti3+ and/or Ti2+ ions.

S.Melsheimer, A.Rahmel, M.Schutze: Oxidation of Metals, 1997, 47[3-4], 205-13